Serial fan assembly and air-guiding structure thereof

ABSTRACT

A serial fan assembly includes a first fan, a second fan and at least one air-guiding structure. The first and second fans are arranged in serial, and the air-guiding structure is disposed therebetween, for guiding an airflow to follow a direction parallel to an axial direction of the serial fan assembly when the airflow exits from the first fan and enters the second fan, thereby increasing air volume and air pressure of the serial fan assembly and reducing noise during operation. Also, power loss is compensated, and flexibility of assembly and fabrication are improved.

This Non-provisional application claims priority under U.S.C.§ 119(a) on Patent Application No(s). 095109998 filed in Taiwan, Republic of China on Mar. 23, 2006, the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a fan assembly, and in particular to a serial fan assembly and an air-guiding structure thereof with enhanced air volume and air pressure and reduced noise.

DESCRIPTION OF THE RELATED ART

As efficiency of the electronic devices increases, heat dissipation apparatus or heat dissipation system becomes necessary. If heat energy produced by electronic devices can not be exhausted appropriately, the electronic device will suffer from reduced efficiency and damage. Heat dissipation apparatus is especially important in microelectronics, such as integrated circuits. With the development and improvement of the integration and package technology, the integrated circuits continuously reduce in size, resulting in relatively high accumulated heat energy per unit. Thus, researches on high-efficient heat dissipation apparatus become the emphasis in the electronic industry.

Fans are the most common heat dissipation apparatus used, but airflow produced by a single fan may not be sufficient to dissipate heat from the electrical parts. Further, breakdown of a single fan can affect operation of the electronic device. Accordingly, another fan can be paired with the single fan in series, as shown in FIG. 1A. The first fan 10A and the second fan 10B, both axial fans, are arranged in series.

FIGS. 1A and 1B are schematic views of two fans showing the relative position of blades and static blades and airflow therebetween. The blades 12 a, 12 b of the first fan 10A and the second fan 10B rotate in an X-direction. After entering the first fan 10A in V1-direction, airflow is slanted in V2-direction by the blades 12 a. Although the static blades 14 a disposed at the outlet of the first fan 10A partially guide airflow back to the original direction from V2-direction, airflow exiting the first fan 10A is adjusted to V3-direction which is not same as V1-direction.

Because the first fan 10A and the second fan 10B are arranged in series, airflow from the first fan 10A enters the second fan 10B directly in V3-direction. However, the blades 12 b impel the airflow to slant in V4-direction. Although the second fan 10B also has static blades 14 b disposed at the outlet thereof, such that after the airflow passing the static blades 14 b in V4-direction, airflow exiting the second fan 10B is adjusted to V5-direction.

Because the fans 10A, 10B rotate in the same direction, the rotating direction X of the blades 12 b of the second fan 10B is parallel to the horizontal vector of airflow V3, this reduces the speed of the rotor 12 b relative to airflow and limits output of the second fan 10B when two fans are assembled. Although the design of the static blades are provided to improve the efficiency of the fan, outlet airflow is not completely guided back to its original direction when the airflow enters another fan. Considering that if airflow is completely guided back to its original direction, the performance of a single fan is reduced. As the results, the work done by the second fan only reaches 30-80 percents of the work done by the first fan. If more than two fans are arranged in series, the efficiency of the subsequent fans is weakened, whereby failing to accomplish the purpose of the serial fan assembly.

Further, the blades 12 a and 12 b of the conventional fan assembly are too close to each other, resulting in disordered airflow between the outlet of the first fan 10A and the inlet of the second fan 10B. When two fans are arranged in series, noise is increased, limiting usage.

BRIEF SUMMARY OF THE INVENTION

The invention provides a serial fan assembly. An air-guiding structure is disposed between two or more serially arranged fans. The air-guiding structure guides airflow into the fans in a direction parallel to an axial direction of the serial fan assembly, whereby raising air volume and air pressure of the serial fan assembly and reducing noise during its operation.

The invention provides another serial fan assembly and air-guiding structure thereof. The air-guiding structure and at least two fans are arranged in series for increasing air volume and air pressure of the serial fan assembly and reducing noise during operation. Also, power loss is compensated, and flexibility of assembly and fabrication are improved.

According to the invention, an air-guiding structure is provided. The air-guiding structure operates with a serial fan assembly, and the serial fan assembly includes at least one first fan and at least one second fan. The air-guiding structure is disposed between the first fan and the second fan for guiding an airflow to follow a direction parallel to an axial direction of the serial fan assembly when the airflow exits from the first fan and enters the second fan, thereby increasing air volume and air pressure of the serial fan assembly Additionally, the air-guiding structure and the serial fan assembly are independent, and can be combined together or detached from each other by wedging, screwing or adhering.

The air-guiding structure described includes at least one guiding panel, the shape of which is radial, spiral, or irregular. Alternatively, each guiding panel is flat or winged, and arranged radially. In addition, the air-guiding structure includes a housing, and the guiding panel is substantially flush with the housing, or a portion of the guiding panel extends out of the housing which is adjacent to the first fan.

The invention provides another serial fan assembly including at least one first fan, at least one second fan and at least one air-guiding structure. The first and second fans are arranged serially, and the air-guiding structure is disposed therebetween for guiding an airflow to follow a direction parallel to an axial direction of the serial fan assembly when the airflow exits from the first fan and enters the second fan, thereby increasing air volume and air pressure of the serial fan assembly. The first fan and the second fan are axial fans. The air-guiding structure and the serial fan assembly are independent, and can be combined together or detached from each other by wedging, screwing or adhering.

In the serial fan assembly described, the air-guiding structure includes at least a guiding panel, the shape of the guiding panel is radial, spiral, or irregular. Alternatively, each guiding panel is flat or winged, and arranged radially. In addition, the air-guiding structure includes a housing, and the guiding panel is substantially flush with the housing, or a portion of the guiding panel extends out of the housing which is adjacent to the first fan.

In the serial fan assembly described, the first fan or the second fan includes an outlet and a plurality of static blades, disposed at the outlet radially for guiding airflow out of the outlet. The static blades and the frame of the first fan or the second fan are integrally formed as a single piece. The first fan or the second fan includes a plurality of blades, the static blades and the blades thereof slanted upwardly. The static blades are flat, triangular, trapezoid, or winged in cross-section, or each of the static blades has at least one curved surface, cambered surface, curved line, cambered line, or a straight center line with a curved or cambered outline.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1A is a schematic view of conventional fans arranged in series;

FIG. 1B is a schematic view of the two fans in FIG. 1A showing the relative position of their blades and static blades and airflow therebetween;

FIG. 2 is a schematic view of a preferred embodiment showing a serial fan assembly;

FIG. 3A is a sectional view of the serial fan assembly in FIG. 2;

FIG. 3B is a schematic view of the two fans in FIG. 3A showing the relative position of blades and static blades and airflow therebetween;

FIG. 4 is a graph showing characteristic curves of the conventional fans and the serial fan assembly of the embodiment;

FIG. 5A is a top view of an air-guiding structure in FIG. 2;

FIG. 5B is a schematic view of the air-guiding structure in FIG. 2; and

FIG. 6 is a top view of another air-guiding structure in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 shows a preferred embodiment of the invention showing a serial fan assembly. The serial fan assembly 2 includes a first fan 20A, a second fan 20B, and a air-guiding structure 30. The first fan 20A and the second fan 20B are arranged in series, and the air-guiding structure 30 is disposed therebetween for guiding an airflow to follow a direction parallel to an axial direction of the serial fan assembly 2 when the airflow exits from the first fan 20A and enters the second fan 20B, whereby increasing air volume and air pressure of the serial fan assembly. The first fan 20A and the second fan 20B are axial fans. The air-guiding structure 30 and the serial fan assembly 2 are independent, and can be combined together or detached from each other by wedging, screwing or adhering.

FIG. 3A is a sectional view of the serial fan assembly in FIG. 2, and FIG. 3B is a schematic view of two fans in FIG. 3A showing the relative position of blades and static blades and airflow therebetween. The blades 22 a, 22 b of the first fan 20A and the second fan 20B rotate in a X-direction as shown in FIG. 3B. After entering the first fan 20A in a V1-direction (an axial direction), the airflow is slanted in a V2-direction by the blades 22 a. However, the static blades 24 a disposed at an outlet of the first fan 20A guide airflow back toward its original direction, such that after passing the static blades 24 a in the V2-direction, the airflow flows out of the first fan 20A in a V3-direction.

Because the air-guiding structure 30 is disposed between the first fan 20A and the second fan 20B, the airflow exits from the first fan 20A and enters the air-guiding structure 30 in the V3-direction. After passing through the air-guiding structure 30, the airflow entering the second fan 20B is parallel to the axial direction of the serial fan assembly 2. That is, the airflow enters the second fan 20B along the V1-direction (axial direction).

For the serial fan assembly 2, the preferred direction of inlet airflow is parallel to the axial direction. By utilizing the air-guiding structure 30, the airflow direction is adjusted, such that the airflow passing through the air-guiding structure 30 can be guided to be parallel to the axial direction. Therefore, when the airflow enters the second fan 20B, the airflow enters in the V1-direction (parallel to the axial direction), so as to allow the work done upon airflow by the second fan 20B to be completed, and enhance the second fan 20B's efficiency.

The comparison chart below shows the power (unit: Watt) of the fans between the conventional fan assembly without an air-guiding structure and the serial fan assembly of the embodiment. The conventional fan assembly and serial fan assembly of the embodiment both use 8-cm fans with static blades, operating at an operating speed of 9800 rpm.

First fan Second fan Conventional fan assembly  41.7 W  18.1 W Serial fan assembly of the embodiment 39.73 W 38.36 W

As shown in the chart, the power of the first fan 20A of the serial fan assembly 2 is only a bit lower than that of the conventional fan assembly, but the power of the second fan 20B of the serial fan assembly 2 is considerably higher than that of the conventional fan assembly. Also, the power consumption by the first fan 20A and the second fan 20B is similar. Additionally, FIG. 4 shows a graph of characteristic curve of the conventional fan assembly and the serial fan assembly of the embodiment.

Accordingly, the design of the air-guiding structure 30 provides the power consumption of all fans in serial fan assembly 2 to be nearly the same. In other words, if multiple fans are arranged in series in the assembly, every subsequent fan exhibits approximately the same power consumption as the first fan. Furthermore, because of the air-guiding structure 30, the two fan's abilities are nearly the same, allowing simple design and control of the serial fan assembly. Because each fan in the serial fan assembly has an average ability to work, the power consumption of the serial fan assembly is lower than that of a single fan. Thus, the rotating speed of the serial fan assembly can be increased without altering the original design and efficiency of the overall assembly is also increased.

Referring all to FIGS. 2, 5A and 5B, the air-guiding structure 30 includes a housing 31, at least one guiding panel 32, and a vertical guiding path 33. Each guiding panel 32 is flat or winged (not shown), and each guiding panel 32 is arranged radially, such that the vertical guiding path 33 is formed between the housing 31 of the air-guiding structure 30 and the guiding panel 32. The guiding panel 32 is for guiding the slanted airflow to back toward a direction which is parallel to the axial direction of the serial fan assembly 2, thereby improving the performance of the fan. Also, the guiding panel 32 is substantially flush with the housing 31 of the air-guiding structure 30, or the guiding panel 32 extends out of the housing 31 which is adjacent to the first fan 20A (as shown in FIG. 5), thereby allowing the guiding panel 32 to be near to the blades 22 a of the first fan 20A.

Although the guiding panels 32 in FIG. 5 are arranged radially, the embodiment is not limited thereto. The guiding panels 32 can be spiral (as shown in FIG. 6) or irregular. Referring to FIG. 3A again, the first fan 20A has an outlet 23 a and a plurality of static blades 24 a. The static blades 24 a are disposed at the outlet 23 a of the first fan 20A, and arranged radially for guiding airflow out of the first fan 20A. The second fan 20B has an outlet 23 b and a plurality of static blades 24 b. The static blades 24 b are disposed arranged radially at the outlet 23 b of the second fan 20B for guiding airflow out of the second fan 20B.

The plurality of static blades 24 a and the frame 21 a of the first fan 20A are integrally formed as a single piece. The static blades 24 a are flat, triangular, trapezoid, or winged in cross-section, or have at least one curved surface, cambered surface, curved line, cambered line, or a straight center line with a curved or cambered outline.

Not only the air-guiding structure 30 guides airflow, but also creates a gap between the two fans, thereby increasing the distance between the blades of the two fans of the serial fan assembly 2. The gap provides sufficient space for airflow from the outlet of the first fan 20A (the prior fan), avoiding direct pressurization from the second fan 20B (subsequent fan). Thus, the flow field is smoother than that of the conventional fan assembly. Further, the blades and the static blades of the first and second fans are slanted upwardly, as shown in FIG. 3A. With the smooth airflow, the noised produced by the assembly is successfully reduced. Because of the fans of the embodiment are arranged in series, a lower speed can be applied to the fan achieve the same heat dissipating result, such that the noise of the assembly is reduced.

Comparing the serial fan assembly having an air-guiding structure with the conventional fan assembly under the same condition, both including two 8-cm fans arranged in series operating at an operating speed of 9800 rpm, a sound test 1 meter away from the inlet of the fan. The conventional fan during the rotation has an operating point as 129.04 cfm, and has a noise level measured as 72.4 dB-A under the condition of 0.5 inch H₂O. On the other hand, the operating point of the serial fan assembly of the embodiment has an operating point as 135.05 cfm, and has a noise level measured as 71.9 dB-A under the condition of 0.5 inch H₂O. Therefore, at the same noise level, the serial fan assembly of the embodiment provides improved performance. In serial arranged fan assembly, the design of air-guiding structure can guide airflow in a direction parallel to the axial direction. Not only air volume and air pressure are increased efficiently, noise produced during operation is reduced.

In the serial fan assembly of the embodiment, an air-guiding structure is disposed between two or more serially arranged fans. The air-guiding structure guides airflow into the fans in a direction parallel to an axial direction of the serial fan assembly, thereby increasing air volume and air pressure of the serial fan assembly and reducing noise. Further, power loss is compensated, and flexibility of assembly and fabrication are improved.

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

1. An air-guiding structure, operating with a serial fan assembly, wherein the serial fan assembly comprises a first fan and a second fan; and the air-guiding structure is disposed between the first fan and the second fan for guiding an airflow to follow a direction parallel to an axial direction of the serial fan assembly when the airflow exits from the first fan and enters the second fan, thereby increasing air volume and air pressure of the serial fan assembly.
 2. The air-guiding structure device as claimed in claim 1, wherein the air-guiding structure and the serial fan assembly are independent, and can be combined together and detached from each other.
 3. The air-guiding structure device as claimed in claim 2, wherein the air-guiding structure combines or detaches to the serial fan assembly by wedging, screwing, or adhering.
 4. The air-guiding structure as claimed in claim 1, wherein the air-guiding structure comprising at least one guiding panel.
 5. The air-guiding structure as claimed in claim 4, wherein the air-guiding structure comprising a plurality of guiding panels, and the guiding panel is radial, spiral, or irregularly shaped.
 6. The air-guiding structure as claimed in claim 4, wherein the air-guiding structure comprising a plurality of guiding panels, and each of the guiding panels is flat or winged, and arranged radially.
 7. The air-guiding structure as claimed in claim 4, wherein the air-guiding structure comprises a housing, the guiding panel is substantially flush with the housing, or a portion of the guiding panel extends out of the housing which is adjacent to the first fan.
 8. The air-guiding structure as claimed in claim 1, wherein the first fan and the second fan are axial fans, the first fan or the second fan has an outlet and a plurality of static blades, disposed at the outlet radially, guiding airflow out of the outlet, and the static blades and the frame of the first fan or the second fan are integrally formed as a single piece.
 9. The air-guiding structure as claimed in claim 8, wherein the static blades are flat, triangular, trapezoid or winged in cross-section, or the static blades comprises at least one curved surface, cambered surface, curved line or cambered line in cross-section, or the static blades comprises a straight center line with a curved or cambered outline in cross-section.
 10. The air-guiding structure as claimed in claim 8, wherein the first fan or the second fan comprises a plurality of blades, the static blades and the blades thereof are slanted upwardly.
 11. A serial fan assembly, comprising: a first fan and a second fan, arranged in series; and an air-guiding structure, disposed between the first fan and the second fan, for guiding an airflow from the first fan to the second fan; wherein when the airflow exits from the first fan and enters the second fan, the airflow is guided to follow a direction parallel to an axial direction of the serial fan assembly, thereby increasing air volume and air pressure of the serial fan assembly.
 12. The heat dissipation device as claimed in claim 11, wherein the air-guiding structure and the serial fan assembly are independent, and can be combined together and detached from each other.
 13. The heat dissipation device as claimed in claim 12, wherein the air-guiding structure combines or detaches to the serial fan assembly by wedging, screwing, or adhering.
 14. The heat dissipation device as claimed in claim 11, wherein the air-guiding structure comprising at least one guiding panel.
 15. The heat dissipation device as claimed in claim 14, wherein the air-guiding structure comprising a plurality of guiding panels, and the guiding panel is radial, spiral, or irregularly shaped.
 16. The heat dissipation device as claimed in claim 14, wherein the air-guiding structure comprising a plurality of guiding panels, and each of the guiding panels is flat or winged, and arranged radially.
 17. The heat dissipation device as claimed in claim 14, wherein the air-guiding structure comprises a housing, the guiding panel is substantially flush with the housing, or a portion of the guiding panel extends out of the housing which is adjacent to the first fan.
 18. The heat dissipation device as claimed in claim 11, wherein the first fan and the second fan are axial fans, the first fan or the second fan has an outlet and a plurality of static blades, disposed at the outlet radially, guiding airflow out of the outlet, and the static blades and the frame of the first fan or the second fan are integrally formed as a single piece.
 19. The heat dissipation device as claimed in claim 18, wherein the static blades are flat, triangular, trapezoid or winged in cross-section, or the static blades comprises at least one curved surface, cambered surface, curved line or cambered line in cross-section, or the static blades comprises a straight center line with a curved or cambered outline in cross-section.
 20. The heat dissipation device as claimed in claim 18, wherein the first fan or the second fan comprises a plurality of blades, the static blades and the blades thereof are slanted upwardly. 